The boxes are provided by USPS for free, and if your shipment is going to Zones 1-4, you'll find that this option is usually less expensive than Flat Rate Boxes. Priority Mail Medium Flat Rate Box ...

Sending your mail or packages under the appropriate U.S. Postal Service (USPS ... you with Priority Mail labels, stickers, envelopes and boxes at no extra charge. The 2-pound flat-rate envelope ...

There is no charge for First-Class Mail Forever® stamps. Even if the First-ClassTM postage rate ... you use the USPS. These pre-printed envelopes, Tyvek® mailers, and boxes are environmentally ...